TORONTO — For her debut feature “Novitiate,” writer-director Maggie Betts aimed for a truthful, original depiction of the inner lives of nuns. But she also wanted to pay homage to the 1959 classic “The Nun’s Story,” starring Audrey Hepburn.

Betts says Margaret Qualley, who stars as Sister Cathleen, “had Audrey Hepburn’s wide, lit-from-within eyes. She felt like the young Hepburn character.” In “Novitiate,” which opens Friday, another young postulant admits that she entered the convent because she was inspired by “The Nun’s Story.”

Betts says her extensive research showed this to be true. “Right before Vatican II, there was a surge in girls signing up,” she says, attributing the influx to both “The Nun’s Story” and to the popularity of “Story of a Soul,” the memoir by Saint Thérèse of Lisieux, also known as the Little Flower.

Advertisement

“For some reason, young girls loved the book,” says Betts. “The most exciting thing for me was discovering how passionate these nuns were.” She also recalls reading a biography of Mother Teresa while waiting in an airport several years ago and being struck by the nun’s reference to God as her husband. The book “was drenched in emotion and passion and pain,” says Betts. It occurred to her, she says, that “nuns aren’t fuddy-duddy old ladies. These are romantics to an extreme.”

Get The Weekender in your inbox:

The Globe's top picks for what to see and do each weekend, in Boston and beyond.

At the start of “Novitiate,” Cathleen (as a child played by Eliza Mason) lives with her free-spirit, divorced mother Nora (Julianne Nicholson) in 1950s rural Tennessee. A scholarship to a Catholic school draws Cathleen into the mystery and romanticism of a life devoted to the worship of God and, against Nora’s wishes, she enters a contemplative religious order that’s overseen by the formidable Reverend Mother (Melissa Leo). But between 1962 and 1965, the church, under the direction of Pope John XXIII, issues a series of sweeping changes known as Vatican II. Though progressive in many ways, these changes, in the eyes of a resistant Reverend Mother, diminish the status of nuns and shake the foundation of her belief.

“The sexism is so entrenched in this institution that [church leaders] can make patriarchal ‘I’m your father’ decisions for women and that’s the problem with it,” says Betts, who had no religious background or affiliation when she began her research. “They didn’t invite [nuns] and they didn’t ask them. All this came from research; I didn’t make it up. Many nuns were pissed and many are still fighting for women to become priests. That [activism] grew out of [the fallout from] Vatican II: Women’s groups have gone head-to-head with the Vatican over the years.”

Leo, whose long resume includes her Oscar-winning role as Lowell’s Alice Ward in “The Fighter” (2010), says she’s always wanted to play a nun. “Maybe because I come from a time, not so long from the time that Reverend Mother came from, when [women’s career choices were] perhaps a nurse, a schoolteacher, a whore, somebody’s wife and, oh, a nun.

“Very often, a woman of a certain age that I happen to be are asked to be an instrument in the storytelling rather than a human being of their own design and making,” says Leo. “The Reverend Mother is, by definition, someone who has decided her own destiny.”

Advertisement

Leo admits she wan’t sure “what exactly was being asked of me” when she read the script. “So I asked Maggie if could I come down to Nashville [where “Novitiate” was filmed] a bit early and we met for 17 hours nonstop.”

“Melissa is the hardest-working person I’ve ever seen in my life,” says Betts. “She is so talented but she comes with a page of notes for every line in the movie. Her process is intense. I stayed out of her way; her Reverend Mother is domineering and intimidating but she generated that character out of herself.”

Betts’s only other feature was the 2010 documentary “Carrier,” about AIDS in Africa. (“I left documentaries behind after my first. It’s really tough on you and not many people see them,” she says.) She called on the experience of veteran editor Susan E. Morse, best known for cutting many of Woody Allen’s films, and cinematographer Kat Westergaard, who shot “Carrier” and Betts’s short film “Engram” (2014). Central to the atmosphere of “Novitiate” was the monastery that housed the nuns. Betts found the perfect setting at a former women’s Methodist college on the campus of Vanderbilt University in Nashville.

“We’d started to look for abandoned convents. The Catholic Church is a huge landowner; it’s amazing how many convents are left with one 95-year-old nun living in it. There’s no shortage of these buildings but the archdioceses wanted to read the script first and I did not want that script circulating through the Catholic community,” says Betts.

She and Westergaard wanted to re-create visually what director Fred Zinnemann accomplished in “The Nun’s Story.” That film, says Betts, “is a homage to a lost world . . . it’s so beautifully shot; all those lush rituals. I wanted it to be energetic, to capture the passion these women felt. Even if they’re sitting in silence, their inner workings are always moving and a young girl is so restless. I told [Westergaard], ‘this is a monochrome world. Let’s find the color.’ That’s what gives it a modern vibrancy.”